Develop Reference

Handle Array of Object manipulation

Below I have an array of objects
var data = [{
"time": "1572024707.4763825",
"rssi": "32",
"id": "77777"
}, {
"time": "1572024709.0991757",
"rssi": "32",
"id": "77777"
}, {
"time": "1572024704.4570136",
"rssi": "32",
"id": "555555"
}, {
"time": "1572024708.3903246",
"rssi": "32",
"id": "77777"
}, {
"time": "1572024699.7132683",
"rssi": "32",
"id": "66666"
}]
How can I restructure it to remove the repeating id's with the oldest time
I tried to pull all the unique IDs from the array so I can loop through the data array but then the code started to get too long.
data.forEach(item => {
IDs.push(item.id);
});
var unqIDs = [...new Set(IDs)];
console.log(unqIDs);
the output should look like this
outPutShouldBe = [{
"time": "1572024699.7132683",
"rssi": "32",
"id": "66666"
},{
"time": "1572024709.0991757",
"rssi": "32",
"id": "77777"
}, {"time": "1572024704.4570136",
"rssi": "32",
"id": "555555"
}
]

Create an object mapping ids to the item w/ the earliest time of those with that id:
var keydata = {};
data.forEach(item=>{
var p = keydata[item.id];
if ( !p || p.time>item.time ) {
keydata[item.id] = item;
}});
Now gather up the values in that object:
var newdata = [];
for ( var k in keydata ) {
newdata.push(keydata[k]);
}
or the more elegant (thanks, #TulioF.):
var newdata = Object.values(keydata)

Using forEach() find() filter() and filter() to decide which element to return
var data = [{"time": "1572024707.4763825","rssi": "32","id": "77777"},{"time": "1572024709.0991757","rssi": "32","id": "77777"}, {"time": "1572024704.4570136","rssi": "32","id": "555555"}, {"time": "1572024708.3903246","rssi": "32","id": "77777"}, {"time": "1572024699.7132683","rssi": "32","id": "66666"}]
let resultsArray = []
data.forEach(obj=>{
const foundObj = resultsArray.find(data => data.id === obj.id)
if(foundObj && new Date(foundObj.time) > new Date(obj.time)){
const filteredArray = resultsArray.filter(data => data.id === obj.id)
resultsArray = [...filteredArray , foundObj]
} else if (!foundObj){
resultsArray.push(obj)
}
})
console.log(resultsArray)

You coud take an object as hash table and get the values directly.
var data = [{ time: "1572024707.4763825", rssi: "32", id: "77777" }, { time: "1572024709.0991757", rssi: "32", id: "77777" }, { time: "1572024704.4570136", rssi: "32", id: "555555" }, { time: "1572024708.3903246", rssi: "32", id: "77777" }, { time: "1572024699.7132683", rssi: "32", id: "66666" }],
result = Object.values(data.reduce((r, o) => {
if (!r[o.id] || +r[o.id].time > +o.time) r[o.id] = o;
return r;
}, {}));
console.log(result)
.as-console-wrapper { max-height: 100% !important; top: 0; }

use lodash to sort the array in descending order or ascending order as per your need (desc, asc) and get the zeroth object. try something like this. filter and orderBy
var data = [{
"time": "1572024707.4763825",
"rssi": "32",
"id": "77777"
}, ....];
let idsSet = new Set();
data.map(item=> idsSet.add(item.id));
let idsArr = Array.from(idsSet);
let newArr = [];
idsArr.map(id=>{
let tempArray = data.filter(item => item.id === id);
return newArr.push((_.orderBy(tempArray, ['time'],['desc']))[0]);
} )
console.log(newArr);
console output
[ {
"time": "1572024709.0991757",
"rssi": "32",
"id": "77777"
}, {
"time": "1572024704.4570136",
"rssi": "32",
"id": "555555"
}, {
"time": "1572024699.7132683",
"rssi": "32",
"id": "66666"
}];

Here you can do something like this :
let existMap = {};
data.filter(val => {
if((val.id in existMap) && (val.time>existMap[val.id])) return;
else{
existMap[val.id] = val.time;
return true;
}
})
console.log(result)
The condition can be changed based on requirement. just want to reference for your problem.

Create new javascript object from 2 JSON objects grouped by id

I have below dynamic nested JSON object arrays and I wanted to get the desired output with JavaScript grouped by id from both.
First Array:
[
{
"id": "11",
"name": "emp1",
"location": [
{ "name": "abc", "id": "lc1" }
]
},
{
"id": "11",
"name": "emp2",
"location": [
{ "name": "abc", "id": "lc1" },
]
},
{
"id": "22",
"name": "emp3",
"location": [
{ "name": "xyz", "id": "lc2" }
]
}
]
Second array like below.
[
{
"name": "sub1",
"id": "11"
...
},
{
"name": "sub1.1",
"id": "11"
...
},
{
"name": "sub2",
"id": "22"
...
}
]
Desired Output:
[
{
"id": "11",
"first": [{"name": "emp1"},
{"name": "emp2"}],
"second": [{"name": "sub1"},{"name": "sub1.1"}],
"location": [{"name": "abc"}]
},
{
"id": "22",
"first": [{"name": "emp3"}],
"second": [{"name": "sub2"}],
"location": [{"name": "xyz"}]
}
]
How to get the desired output like above using javascript/angularjs?

I would do it using the amazing Array#reduce function.
Note that I have named your first array as a1, second as a2 and result as res.
a1.reduce(function(arr, obj) {
var existing = arr.filter(function(res) {
return res.id === obj.id
})[0]
if (existing) {
existing.first.push({
name: obj.name
})
} else {
var second = a2.filter(function(res) {
return res.id === obj.id
})
var secondObj = second.length ? second.map(function(sec) {
return {
name: sec.name
};
}) : []
arr.push({
id: obj.id,
first: [{
name: obj.name
}],
second: secondObj,
location: obj.location
})
}
return arr;
}, [])
Here's the working snippet. Take a look!
var a1 = [{
"id": "11",
"name": "emp1",
"location": [{
"name": "abc",
"id": "lc1"
}]
},
{
"id": "11",
"name": "emp2",
"location": [{
"name": "abc",
"id": "lc1"
}]
},
{
"id": "22",
"name": "emp3",
"location": [{
"name": "xyz",
"id": "lc2"
}]
}
]
var a2 = [{
"name": "sub1",
"id": "11"
}, {
"name": "sub1.1",
"id": "11"
},
{
"name": "sub2",
"id": "22"
}
]
var res = a1.reduce(function(arr, obj) {
var existing = arr.filter(function(res) {
return res.id === obj.id
})[0]
if (existing) {
existing.first.push({
name: obj.name
})
} else {
var second = a2.filter(function(res) {
return res.id === obj.id
})
var secondObj = second.length ? second.map(function(sec) {
return {
name: sec.name
};
}) : []
arr.push({
id: obj.id,
first: [{
name: obj.name
}],
second: secondObj,
location: obj.location
})
}
return arr;
}, [])
console.log(res)
.as-console-wrapper {
max-height: 100% !important;
top: 0;
}

var red1 = [{
"id": "11",
"name": "emp1",
"location": [{
"name": "abc",
"id": "lc1"
}]
},
{
"id": "11",
"name": "emp2",
"location": [{
"name": "abc",
"id": "lc1"
}]
},
{
"id": "22",
"name": "emp3",
"location": [{
"name": "xyz",
"id": "lc2"
}]
}
]
var b = [{
"name": "sub1",
"id": "11"
},
{
"name": "sub2",
"id": "22"
}
]
var identication = {}
var result = []
red1.forEach(function(val) {
if (val['id'] in identication) {
var t = {}
t['name'] = val['name']
result[identication[val['id']]]['first'].push(t)
} else {
var t = {}
t['name'] = val['name']
val['first'] = []
val['first'].push(t)
delete val['name']
var identity = result.push(val)
identication[val['id']] = identity - 1;
}
})
b.forEach(function(d) {
if (d['id'] in identication) {
var t = {
'name': d['name']
}
if (!('second' in result[identication[d['id']]])) {
result[identication[d['id']]]['second'] = []
}
result[identication[d['id']]]['second'].push(t)
} else {
var t = {}
for (key in d) {
if (key == 'name')
continue
t[key] = d[key]
}
t['second'] = [{
'name': d['name']
}]
var identity = result.push(t)
identication[d['id']] = identity - 1;
}
})
console.log(result)

How to merge and flat arrays at the same time

I have two arrays of data, one has tree structure and another is just a nested array with details..
What I want to do now is to flat this details array and merge it to tree's structure.
Both details and tree have records with same unique ID.
var tree = [{
"Children": [{
"Children": [],
"ID": "1",
"PendingChange": true,
}],
"ID": "22",
"PendingChange": false,
}];
var details = [{
"Address": {
"Jurisdiction": {
"Name": "United Kingdom"
},
"City": "Waltham Cross"
},
"ID": "1",
"Name": "J"
}];
var finalArray = _.map(tree, function(e) {
return _.extend(e, _.omit(_.findWhere(details, {
ID: e.ID
}), 'ID'));
});
console.log(finalArray);
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
Desired output
var tree = [{
"Children": [{
"Children": [],
"ID": "1",
"PendingChange": true,
"Name": "J"
"Address_City": "Waltham Cross"
"Address_Jurisdiction_Name": "United Kingdom"
}],
"ID": "22",
"PendingChange": false,
}];
Underscore is not a must, I am just stuck with it - https://jsfiddle.net/ey8hqn19/

You could create recursive function with for...in loop that will loop deep tree object and then use find to find object with same id in details and add properties.
var tree = [{
"Children": [{
"Children": [],
"ID": "1",
"PendingChange": true,
}],
"ID": "22",
"PendingChange": false,
}];
var details = [{
"Address": {
"Jurisdiction": {
"Name": "United Kingdom"
},
"City": "Waltham Cross"
},
"ID": "1",
"Name": "J"
}];
function makeTree(data) {
for (var i in data) {
if (typeof data[i] == 'object') makeTree(data[i])
if (i == 'ID') {
var f = details.find(function(e) {
return e.ID == data[i]
})
if (f) {
Object.assign(data, {
"Name": f.Name,
"Address_City": f.Address.City,
"Address_Jurisdiction_Name": f.Address.Jurisdiction.Name
})
}
}
}
}
makeTree(tree)
console.log(tree)

Javascript get name from data by id function

I need to create a function the would return the name of the car when given the id.
I have this data:
{
"cars": [
{
"id": "661",
"name": "ford"
},
{
"id": "657",
"name": "fiat",
},
{
"id": "654",
"name": "volvo",
},
{
"id": "653",
"name": "porche",
},
{
"id": "650",
"name": "mazda",
}
]
}
So I've done this:
function getCarNameFromId(id) {
theData = {
"cars": [
{
"id": "661",
"name": "ford"
},
{
"id": "657",
"name": "fiat",
},
{
"id": "654",
"name": "volvo",
},
{
"id": "653",
"name": "porche",
},
{
"id": "650",
"name": "mazda",
}
]
};
console.log(theData.name);
}
then call it:
function getCarNameFromId('650');
How do I finish this code so I can get the code to return me the name of the id specified?

JS solution
var findCar = function(id) {
var theData = {
"cars": [{
"id": "661",
"name": "ford"
},
{
"id": "657",
"name": "fiat",
},
{
"id": "654",
"name": "volvo",
},
{
"id": "653",
"name": "porche",
},
{
"id": "650",
"name": "mazda",
}
]
};
for (var i = 0; i < theData.cars.length; i++) {
var car = theData.cars[i];
if (car.id === id)
return car.name;
}
}
console.log(findCar("654"));

If you are using any mordenr browser you can use find method to find object from array
function getCarNameFromId(id) {
......
..........
.....
var obj = theData.cars.find( function(el) {
return el.id == id
})
if(obj){
return obj.name
} else {
return ''; // or just without any value.
}
}
if still want to support old browsers i would recommand to use lodash.js or underscore.js

cars.find(car => car.id === id).name
Reference:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions

Building new JSON from existing one

I want to build an new JSON from existing one. The source has sections and rubrics that I no longer need for a listing. The new object called 'items' should have an array of the items.
The final JSON should be sorted by attribute 'name' and look like
{
"items": [
{
"id": 10000006,
"name": "Boah"
},
{
"id": 10000013,
"name": "Gut"
},
{
"id": 10000003,
"name": "Ipsum"
},
{
"id": 10000001,
"name": "Lorem"
},
{
"id": 10000005,
"name": "Lorum"
},
{
"id": 10000004,
"name": "Name"
},
{
"id": 10000002,
"name": "Stet"
}
]
}
For building the new JSON I get this source:
{
"sections": [
{
"name": "FooBar",
"rubrics": [
{
"name": "Foo",
"items": [
{
"id": 10000001,
"name": "Lorem"
},
{
"id": 10000002,
"name": "Stet"
},
{
"id": 10000003,
"name": "Ipsum"
}
]
},
{
"name": "Bar",
"items": [
{
"id": 10000004,
"name": "Name"
},
{
"id": 10000005,
"name": "Lorum"
},
{
"id": 10000006,
"name": "Boah"
}
]
}
]
},
{
"name": "BlahBloob",
"rubrics": [
{
"name": "Bla",
"items": [
{
"id": 10000013,
"name": "Gut"
}
]
},
{
"name": "Bloob",
"items": [
{
"id": 10000014,
"name": "Name"
},
{
"id": 10000015,
"name": "Lorem"
}
]
}
]
}
]
}
What do you think? How can I do this with plain JavaScript or maybe TypeScript?
Thanks for reading and have time for my question. And thanks for reply in advance.

Here you go. You just need to iterate over each rubric of each section of your source to get the items. At the end, sort your list of items by items, and you're done.
This example uses ES6 syntax, but it's easy to convert it to ES5 if needed.
function extractItems(source) {
const items = [];
for (const section of source.sections) {
for (const rubric of section.rubrics) {
items.push(...rubric.items);
}
}
items.sort((a, b) => a.name.localeCompare(b.name));
return { items };
}

A more functional approach use map and reduce to pick the rubrics and merge them.
data.sections
.map(section => section.rubrics) // get rubrics
.reduce((a, b) => a.concat(b)) // merge rubrics
.map(rubric => rubric.items) // get items from each rubric
.reduce((a, b) => a.concat(b)) // merge items
.sort((a, b) => a.name.localeCompare(b.name)); // sort

function(oldObj) {
var newObj = {
"items": []
};
oldObj.sections.forEach(function(section) {
section.rubrics.forEach(function(rubric) {
rubric.items.forEach(function(item) {
newObj.items.push(item);
});
});
});
newObj.items = newObj.items.sort(function(a, b) {
if (a.name < b.name) { return -1; }
if (a.name > b.name) { return 1; }
return 0;
});
return newObj;
}
And simply use JSON.parse() and JSON.stringify() to convert JSON to and from objects.

It might help you
var data ={
"sections": [
{
"name": "FooBar",
"rubrics": [{"name": "Foo", "items": [{"id": 10000001,"name": "Lorem"}, {"id": 10000002,"name": "Stet"}, {"id": 10000003,"name": "Ipsum"}]
}, {
"name": "Bar",
"items": [{
"id": 10000004,
"name": "Name"
}, {
"id": 10000005,
"name": "Lorum"
}, {
"id": 10000006,
"name": "Boah"
}]
}]
}, {
"name": "BlahBloob",
"rubrics": [{
"name": "Bla",
"items": [{
"id": 10000013,
"name": "Gut"
}]
}, {
"name": "Bloob",
"items": [{
"id": 10000014,
"name": "Name"
}, {
"id": 10000015,
"name": "Lorem"
}]
}]
}]
};
var itemObj = {};
var itemArr = [];
var sections = data.sections;
for(var i=0;i<sections.length;i++)
{
for(var j=0;j<sections[i].rubrics.length;j++){
for(var k=0;k<sections[i].rubrics[j].items.length;k++){
var itemObj;
itemObj['id'] = sections[i].rubrics[j].items[k].id;
itemObj['name'] = sections[i].rubrics[j].items[k].name;
itemArr.push(itemObj);
}
}
}
var finalObj = {"items":itemArr};
console.log(finalObj);
JSFiddle